Device for harnessing solar energy with vapor insulating heat transfer core

ABSTRACT

A solar collector is provided, in one embodiment. The solar collector comprises a heat core to convert incident radiation into heat; a wicking layer spaced from the heat core to absorb infrared radiation emitted by the heat core due to the conversion of incident radiation into heat; an inlet to introduce a heat transfer fluid into the wicking layer; wherein the absorption of the infrared radiation is by the heat transfer fluid in the wicking layer and causes a portion of the heat transfer fluid to enter into a vapor phase thereof which propagates into the heat core where it undergoes heating; and an outlet to transport the heated vapor phase of the heat transfer fluid out of the collector.

This application is a continuation-in-part of U.S. Ser. No. 12/623,337and U.S. Ser. No. 12/830,273.

FIELD

Embodiments of the invention relate to devices and methods to harnesssolar radiation as an energy source.

BACKGROUND

Solar collectors are devices designed to convert solar radiation intoheat that can be used to perform work.

One new design of a solar collector was described in co-pending U.S.patent application Ser. No. 12/623,337, and U.S. Ser. No. 12/830,273 thespecifications of which are hereby incorporated by reference. Theimproved performance of this collector derives from the fact that alight absorbing heat transfer core (HTC) resides within the volume of aninfrared absorbing heat transfer or working fluid, including but notlimited to water or other synthetic fluids similar in composition to the“Dowtherm” line of heat transfer fluids manufactured Dow ChemicalCorporation. A primary requirement of the fluid is that it besubstantially transparent in the visible region of light, and highlyabsorbing in the infrared region. The HTC includes a light absorptioncomponent that converts incident solar flux into heat, which istransferred to the heat transfer or working fluid as it passes towardsand through the body of the HTC. Heat that radiates from the HTC in theform of infrared radiation is absorbed by the working fluid and thusprevented from escaping to the ambient environment. The lower radiativelosses result in overall improved performance of the collector. A designfor a solar thermal energy conversion system was described in co-pendingU.S. patent application Ser. No. 12/396,336 which is hereby alsoincorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 of the drawings shows two plots which illustrate the infraredabsorption properties of water.

FIG. 2 of the drawings illustrates a prior art embedded absorber solarcollector, and a side view of an embedded absorber solar collectorintegrated with a regenerator and a condenser.

FIG. 3 of the drawings shows a side view of both a planar and acylindrical solar collector containing a vapor insulated heat transfercore with low pressure vapor output in accordance with embodiments ofthe invention.

FIG. 4 of the drawings shows a side view of both a planar and acylindrical solar collector containing a vapor insulated heat transfercore with high pressure vapor output, in accordance with embodiments ofthe invention.

FIG. 5 of the drawings shows a schematic diagram for a thermal energyconversion system incorporating a solar collector array with lowpressure vapor output.

FIG. 6 of the drawings shows a schematic diagram for a thermal energyconversion system incorporating a solar collector array with highpressure vapor output, in accordance with one embodiment of theinvention.

FIG. 7 of the drawings shows a schematic diagram for a data processingfacility supplied by cooling and heating resource from a solar thermalenergy conversion system, in accordance with one embodiment of theinvention.

FIG. 8 of the drawings show a schematic diagram for a solar thermalapplication dedicated solely to the generation of a cooling resource, aheating resource, or a combined cooling and heating resource, inaccordance with one embodiment of the invention.

DETAILED DESCRIPTION

In the following description, for purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of the invention. It will be apparent, however, to oneskilled in the art that the invention can be practiced without thesespecific details.

Reference in this specification to “one embodiment” or “an embodiment”means that a particular feature, structure, or characteristic describedin connection with the embodiment is included in at least one embodimentof the invention. The appearances of the phrase “in one embodiment” invarious places in the specification are not necessarily all referring tothe same embodiment, nor are separate or alternative embodimentsmutually exclusive of other embodiments. Moreover, various features aredescribed which may be exhibited by some embodiments and not by others.Similarly, various requirements are described which may be requirementsfor some embodiments but not others.

Plot 100 of FIG. 1 shows the spectrum of radiation emitted by the sunthat strikes the earth's surface. In general it is useful to absorb andconvert as much of this energy as possible. Plot 100 illustrates thatthe bulk of the received energy from the sun resides between thewavelengths of 200 nm to 2400 nm. Plot 102 illustrates the absorptionspectrum of water, which is one candidate heat transfer fluid. As can beseen, water is extremely transparent to light in the wavelengths from200 nm to 1000 nm. As the wavelength increases, the absorption ofincident light increases dramatically. This property may be used toadvantage, and there is evidence to suggest that other heat transferfluids exhibit similar performance.

Referring now to FIG. 2, solar collector 202 is shown being illuminatedby incident solar flux 200. This light is transmitted into the interiorwhere it is absorbed by porous heat transfer core 204. The heat transfercore 204, because it has a light absorption component on its surface,subsequently rises in temperature due to absorption of the incominglight. Incoming heat transfer fluid 214, which could be water, forexample, flows along the exterior of the heat transfer core 204 in thedirection indicated by the solid arrows 207 and 210. As it passesthrough the body heat transfer core 204, it rises in temperature viaconduction of heat from the heat transfer core 204. The heated fluid 214then passes out of the solar collector 202 through the interior of theheat transfer core 204 indicated by dashed arrows 212. The output heatedfluid 216, can be used to provide useful heat to external componentswhich are in fluid communication with the collector 202.

FIG. 2 also shows a conceptual view another collector 220. The collector220 includes an exterior housing 238 which contains a heat transfer core236, and is mechanically and thermally bonded to regenerator/condenserassembly 228. In operation, cooled vapor 222, from an exterior energythermal energy conversion system, propagates in the direction indicatedby dashed arrow 224. As it passes through this passage it gives up heatto the assembly and is cooled. After it makes the turn at 226, itcontinues to propagate along in the direction indicated by line 230,which represents condensed fluid. The bottom exterior surface ofregenerator/condenser assembly 228 is exposed to the ambientenvironment. This provides a means to condense the incoming vapor 222 byproviding a thermally conducting path to the environment. Thus heat isrejected to the environment enabling the condensation. Gap 240 providesthermal isolation between the incoming vapor 222, and the condensedfluid 230. Capillary pump 232 provides a means for pumping the condensedfluid 230 along path 234, into the body of the heat transfer core 236,where it is subsequently heated into a vapor 242, which can then beutilized by an external thermal energy conversion system.

FIG. 3 shows a planar solar thermal collector 300, containing a heattransfer core (HTC) 310 similar in structure to that which was describedin U.S. patent application Ser. No. 12/623,337, and shown in FIG. 2. Inone embodiment, the HTC 310 may comprise a monolithic thermallyconducting metal (copper or aluminum for example) or carbon foam matrixwhose outer surface, or entire surface, has been coated or treated witha thin film or stack of thin films such that light that is incident onthe outer surface is completely or substantially absorbed. In thisembodiment the material may be substantially porous with a pore size anddensity to optimize the transfer of heat via conduction from thematerial of the HTC 310 to any vapor which is passing through it, whileoptimizing the pressure drop through the HTC 310. The light absorbingsurface treatment may also be in the form of a chemical etching processwhich produces a microscopically textured or roughened surface whosegeometry encourages the absorption of incident light. In anotherembodiment the core may be in the form of a bonded pair of plates whosesurface has been perforated via machining or chemical means, to producea network of through holes, and whose interior is filled with a highlythermally conductive foam material, as described above, or with a metalwire or fiber mesh, or a structured metal fin array which issubstantially porous. Many alternative fill materials and structures maybe utilized. The porosity of the core and its fill material isdetermined by the desired heat transfer coefficient, between the coreand vapor propagating inside, and the desired characteristics includingpressure drop and velocity of any vapor transported through the core.The porosity may vary in the range of 20-80% more or less. The pore sizehas a similar impact on these characteristics and may vary in the rangeof tens to hundreds of microns. The interior of the core may be hollowand provide a space which could be at least several times the size ofthe pores in the core. The light absorbing coating on the HTC shouldserve to minimize emission in the near and mid infrared regions as well.HTC 310, is illuminated by solar flux 302 emitted by the sun.Transparent front plate 304 allows for the passage of solar flux 302, sothat it may be absorbed by the HTC 310. It comprises a material which ishighly transparent to visible light, such as glass or other suitablytransparent and environmentally robust material. Transparent front plate304 is hermetically bonded to housing 306 such that it can sustain avacuum and prevents the passage of gasses in the environment into thehousing 306, and the passage of gasses from the interior of the housing306 to the environment. The primary characteristics of the housing 306are that it preclude the passage of such gasses and vapors, bemechanically robust for exposure to an external environment, and bethermodynamically compatible with the transparent front plate 304.Transparent front plate 304 may also have resident on one or both of itssurfaces an antireflective coating one type or another, of which thereare many designs known to those skilled in the art of designing andmanufacturing antireflective coatings. Many materials including metals,and fiberglass or carbon composites suitably coated with barriermaterials, can provide this function. The transparent front plate 304and housing 306 have external conduits 318 and 312 which provide a meansfor the input of condensed heat transfer/working fluids (HTF) 322, andoutput of heated vaporized HTF 320, respectively. Additionally thetransparent front plate 304 and housing 306 have a porous or surfacestructured wicking material 308, resident on the entire extent of theirinterior surface. This material is dimensioned and structured so as toact like a capillary wick for the HTF which resides within it.

A porous wicking material means a film whose interior is laced with anetwork of continuous interconnected passages to allow for the pumping,via capillary forces, and propagation of the HTF. A surface structuredwicking material has a surface (an array of microscopic grooves forexample) which has been defined to promote the capillary pumping andpropagation of HTF along the interior surface. Many variations on porousand surface wicks are possible and well understood by those skilled inthe art of fabricating capillary wicks, especially for use in heatpipes. Characteristics of the wick on the interior surface of the frontplate include high transparency to visible light, and a refractive indexclose to that of the HTF to be utilized. One candidate is Teflon, butthere are a variety of plastics and oxide materials which may suffice.Characteristics of the wick on the interior surface of the housing donot require transparency to visible light. The transparent front plate304, housing 306, HTC 310, surface structured wicking material 308, andconduits 312,318 collectively define a planar solar collector. Planarmeans that the lateral dimensions (as extending left to right on thepage, and into the page) are substantially larger than the vertical(thickness) dimension (extending top to bottom on the page). Typicaldimension are in the range of several to tens of centimeters for thethickness, and 0.5 to 1 meter for the lateral dimension. As describedwithin the aforementioned patent applications, some kind of interiorsupport structure array may be required if the collector is to operateat interior pressures which are sub-atmospheric. The overall design goalof such supports is to minimize the transfer of heat via conduction fromthe core to the transparent front plate, and housing 306, whileproviding mechanical support between these two components to withstandthe pressure of the external atmosphere.

The light from the solar flux 302, which is absorbed by the HTC 310, issubsequently converted into heat, thus the temperature of the corerises. Subsequently heat radiated from the core in the form of infraredradiation 314, is incident on the HTF which is resident within or on thesurface of the interior wick. Because the heat HTF absorbs in theinfrared, the temperature of the HTF is subsequently increased andresults in evaporation of the HTF. HTF input conduit 318, is in fluidcommunication with the wick. Thus as the HTF is evaporated it isreplaced by additional HTF supplied via the capillary forces which acton the HTF to pump it through the wick. The wick is designed to have apumping capacity which is at least equal to, though nominally somewhatexceeds, the rate at which evaporation extracts the fluid under normaloperating conditions. The rate of evaporation is determined by a numberof factors including the initial collector internal pressure, thecharacteristics of the core and the wick, the intensity of the solarflux, as well as the temperature of the condensed HTF entering thecollector among others. As a consequence it may be necessary toconstantly modify the incoming flow rate of HTF 322, in order to preventsurface structured wicking material 308 from drying out (at high inputenergy levels) or flooding (at low input energy levels), or if otherinternal or external characteristics of the collector change over time.

The HTF vapor 316 emerges from the wick at a temperature which isslightly above the saturation temperature of the HTF. Due to theresulting increase in pressure the HTF vapor flows towards the HTC 310.The vapor undergoes a small amount of superheat due to the infraredradiation 314 it absorbs, and as it passes through the body of the coreundergoes more substantial superheating due to further absorption ofradiation and conduction to body of the core. The result is asuperheated vapor 320, which is output via conduit 312, and which can besubsequently utilized in a solar thermal energy conversion system to bedescribed later in the specification. Typical pressure of thesuperheated vapor 320 is less than 1 bar under normal externalenvironmental temperatures.

Overall this collector exhibits superior operation and lower thermallosses because the heat, absorbed by the HTF in the wick, is transferredto the wick via evaporation. In the aforementioned applications, and thecollector 202 shown in FIG. 2, this heat transfer is done via fluidictransfer from the wick to the core. Because HTF vapor has a much lowerthermal conductivity, lower thermal losses can be sustained at lowerflow rates. The end result is the collector is capable of achievinghigher outlet temperatures for a given amount of incident solar flux.

Referring again to FIG. 3, another solar collector 330 is shown which isidentical in function and operation to the collector 200. In this case,however, a cylindrical geometry is shown which can be useful forapplications wherein concentrating optics is used to increase the totalflux incident on the collector. Transparent cylinder 334, like thetransparent front plate of collector 300, is made from a material suchas glass which could be strengthened by chemical or thermal treatment,and may have antireflective coatings on its surfaces. For purposes ofthis illustration one end of the cylinder is shown to be hermeticallysealed. In certain applications one or both ends of the cylinder may notbe sealed as the cylinders may be connected in a series fashion tocreate a collectively longer cylinder. The interior of cylinder 334 isalso lined with a transparent wicking material 336, which is in fluidiccommunication to incoming condensed HTF 332. Suspended in the center ofthe cylinder is porous absorber core 338 which comprises materials whichare highly thermally conductive, have internal pore sizes ranging fromtens to hundreds of microns, and are also treated so that the exposedsurface, or perhaps the entire porous matrix, is highly absorbing tovisible light as in collector 300. Alternative means for achievingporosity, such as the perforation described in collector 300, may alsoapply in this configuration. The core may be hollow to providesupplemental space for vaporized HTF 342, to be output with relativeease. Similarly the interior may also contain a heat conducting fillmaterial as described in collector 300. Similarly the interior may alsocontain a heat conducting fill material as described in collector 300.Sunlight passes through the cylinder and is incident on the core 338where it is subsequently turned into heat. The resulting radiation 344drives evaporation of the HTF resident in the wick, which is sustainablyreplaced by the pumping properties of the wick by incoming fluid 332.This evaporated heat transfer fluid 340, is forced via pressuredifferences to propagate into the absorbing core 338, where it undergoessuperheating via some combination of conductive and radiant heattransfer from the core 338. The resulting vapor 342, is output to besubsequently used in a thermal energy conversion system or other systemprocess which can make use of heat.

Referring now to FIG. 4, another variation of the planar collector 400is shown. In many ways this design is also similar to the collectorshown in FIG. 1. Transparent front plate 404 is bonded to hermeticallysealed housing 410. The interior surfaces of both are coated with a wickmedium 408, which is in fluid communication with inlet conduits 420.Absorber core or core 412 has a surface which has been treated or coatedin a way to maximize the absorption of visible light and minimize it'semission of infrared radiation.

In this case the core 412, is not porous but is a solid hollow metalcylinder which is capable, due to its material properties anddimensions, of withstanding high internal pressure. The bulk of theinterior of the absorber core is filled with a porous material, thesuperheat matrix 414, nominally a highly thermally conductive metal,with a pore size and porosity similar to the cores described in FIG. 3.

One end of the core is in fluidic communication with and hermeticallysealed too, outlet conduit 424. Thus superheated HTF vapor 426, may onlybe output via conduit 424. The absorber core is plugged on one end byhigh pressure capillary pump 416. Capillary pump 416 is a porousmaterial construct of high mechanical strength. It may be comprised ofany one or a combination of materials including metals, metallic oxides,and carbon which have been produced in the form of a foam or perhaps,via a sintering process, into a porous network. There are a variety ofother techniques for producing such materials as known by those who areskilled in the art, especially the art of manufacturing porousfiltration components. It may comprise materials of different porositiesand pore sizes. High pressure capillary pump 416, is shown in greaterdetail in 428. In this example the pump has two regions of porosity andpore size, regions 430, and 432, though it may have more. Porous region430 has a pore size on the order of tens to hundreds of microns and aporosity nominally exceeding 40%. Porous region 432 has a pore size ofmicrons or less and a porosity nominally exceeding 50%. Due to its poresize, region 430 performs the function of pumping a fluid at relativelylow pressure, perhaps in the range of 0.1 to 5 bar, in addition toproviding mechanical support to region 432. This mechanical support isrequired because of the high pressure differential which must besustained between the interior of the core and its exterior. Due to itspore size, region 432 is capable of pumping fluids at higher pressuresranging from 10 bar to 50 bar or more.

The transparent front plate 404, housing 410, wick 408, the core 310 andits components 416 and 414, and the conduits 424 and 420, collectivelycomprise a high pressure planar collector. Planar refers to the samedimensional constraints as described in FIG. 3.

Transparent front plate 404, allows incident light 402, to be absorbedby the core 412. As the core heats up due to the incident solar flux, itbegins to radiate thus heating the HTF within the wick 408. Properdesign of both the wick 408, and the high pressure capillary pump 416,as well as proper maintenance of the internal pressure, among otherfactors, prevents or inhibits evaporation of the HTF which flows towardscapillary pump 416. Capillary pump 416, due to its porosity and poresize is capable of pumping the heated HTF into the superheat matrix 414against high pressure. Heat which is conducted from the body of the coreto the capillary plug causes the fluid to vaporize inside the core andpropagate into superheat matrix 414. This drives the pumping ofadditional fluid, from wick 408, to replace it. Pressure differenceswithin the superheat matrix 414, drive the vapor to propagate towardsthe other end of the core, and the HTF vapor absorbs heat via radiativeand conductive processes as it does so. Because of the mechanicalproperties of the superheat matrix 414, and the pumping properties ofthe capillary pump 416, this vapor may be achieve high pressuresexceeding 10 bar without damage to the collector. The advantage of beingable to sustain high output pressures will be detailed later in thisspecification.

Referring again to FIG. 4, a cylindrical solar collector 440 is shownwhich is identical in function and operation to planar collector 400 ofthe same Figure. A transparent cylinder 444 has a transparent wick 446,resident on its interior surface. Core 450, is sealed by capillary pump452 at one end, and the bulk of its interior occupied by superheatmatrix 454.

Similar in operation to the planar collector 400, sunlight passesthrough the cylinder wall of the transparent cylinder 444 where it isincident on core 450, and subsequently converted into heat. Theradiation from the core heats up the HTF 456, which is propagating inwick 446, and is finally pumped via capillary pump 512, into theinterior of the absorber core. There it is turned into a vapor, thensuperheated by passage through superheat matrix 454, and output in theform of high pressure superheated vapor 458. Output temperatures fromthe collectors described in FIGS. 3 and 4 can theoretically achievetemperatures exceeding 300 C without the need for mechanisms fortracking the sun or optics for concentrating the solar flux. Withconcentration, which can take the form of parabolic troughs, Fresnelarrays, parabolic dishes, and other techniques well known anddemonstrated commercially, output temperatures can reach even highervalues.

Referring now to FIG. 5, two heat transfer loops are illustrated. Thefirst, the heat transfer fluid loop, comprises vapor and fluid loopsections 504 and 506 respectively, which collectively form a continuoushermetically sealed conduit loop through which heat transfer vapor andfluid may flow. The second loop, the working fluid loop, comprises vaporand fluid loop sections 518 and 520 respectively which collectively forma separate hermetically sealed conduit loop. The loops are coupled viaheat exchangers 510, 512, and 514. In general, heat exchangers 510, 512,and 514, provide a means for transferring heat from one conduit toanother without mixing the two fluids between which the heat isexchanged. The overall goal is to effectively transfer heat from theheat transfer loop, to the working fluid loop.

During operation, low pressure solar collector array 502 (which couldcomprise planar and/or cylindrical collectors as described earlier), isilluminated by the sun 500 and the resulting heat in the form of asuperheated low pressure vapor is carried away via vapor conduit 504.

Some portion of this heat may be stored in thermal energy storage unit508 which is connected to conduit 504. Thermal energy storage unit 506,is a sealed tank capable of supporting high internal pressures andfilled with a quantity of water and/or water vapor at saturation. Inputand extraction of thermal energy may be accomplished by a number ofmeans including those described by the aforementioned U.S. patentapplication Ser. No. 12/396,336. The heat from conduit 504 passesthrough superheater heat exchanger 510 which lowers the temperature ofthe vapor, and provides a means for transferring heat from the vapor inconduits 504 to the vapor in conduits 516. The vapor continues to flowto boiler heat exchanger 512, which lowers the temperature of the vaporfurther, transferring additional heat to the fluid passing through theheat exchanger via conduit 518. Finally the vapor passes through preheatheat exchanger 512, where it is condensed into a liquid. This liquidpasses into fluid conduit 506 where it is pumped via pump 516, back intothe collector array 502 where it can be reheated. This represents atypical solar thermal heat transfer loop though in this case the pump,516, may not be necessary or its required pumping capacity lowered dueto the inherent capillary pumping capacity of the solar collector array.

The temperature of evaporation in the collector is determined in part bythe total volume of HTF and vapor which exists in the HTF loop. Thiscombined volume contributes to the internal operating pressure of thesystem or the saturation pressure. The volume and therefore operatingpressure of the HTF loop, can be determined when the system is assembledand/or changed dynamically during operation to minimize the temperaturedifference between the environment and the condensed HTF inside thewick. One simple means for achieving this dynamic control would be toincorporate a hermetically sealed reservoir 526, which is coupled to thesystem via a pump and valve mechanism. The pump could be used todecrease the operating pressure of the system by pumping excess vapor orfluid into the reservoir, and the valve could be used to release thevapor/fluid from the reservoir into the system. The pump and valvemechanisms would operate under electronic or computer control to keepthe internal system operating pressure at a level which relates to theenvironmental conditions including but not limited too ambienttemperature, solar flux intensity, and wind conditions. Many means existfor controlling internal pressure which are well known to those skilledin the art of pressurized network design. In general, keeping thetemperature difference between the environment and the HTF in the wickfurther reduces heat losses to the environment and is the goal of thecomputer control system.

With respect to the working fluid loop, condensed working fluid ispumped via pump 522 through fluid conduit 520 into heat exchanger 514and receives sufficient-heat so that its temperature is raised to theboiling point. After the heated working fluid passes through heatexchanger 512, the additional heat boils it and produces a vapor streamwhich flows into vapor conduit 518. The resulting working fluid vaporstream passes through heat exchanger 518 where it is superheated. Afterthis stage the superheated vapor then passes through utility generationunit (UGU) 524, where it is converted into various utilities comprisingsome combination of electricity, heat and cooling resources forindustrial, residential or other uses. Because the generation ofelectricity from a heat source generally requires a working fluid vaporunder high pressure, two separate loops are required in order tomaintain low pressure on the heat transfer loop side, and high pressureon the working fluid loop side. If the suite of utilities supplied byUGU 524, does not include electricity, then only one loop is requiredand heat exchangers 510, 512, and 514, can be eliminated.

Referring now to FIG. 6, a single working fluid heat transfer loop isshown comprising vapor loop sections 604, and fluid loop sections 614.During operation solar flux incident on high pressure collector array602, results in a high pressure superheated vapor stream which flowsinto vapor conduit 604. In a fashion similar to that described for FIG.5, heat may be added to or extracted from thermal energy storage unit606 as conditions of operation merit. The superheated vapor istransported to expander 608 which is in the form of one of many designsfor expansion units (turbines, tesla engines, screw expanders, etc.)which are manufactured commercially. The function of the expander is toconvert the energy of the expanding vapor into mechanical work which canbe used to drive electric generator 610 to generate electricity. Theexpanded vapor emerging from the expander still has useful heat, thus itflows to UGU 612, which converts and/or transfers this heat intoheating/cooling resources as described above. The UGU 612, extractssufficient heat so that the vapor is condensed and flows into fluidconduit 614. Pump 616 then transports the fluid back to the collectorarray where it can be reheated and converted back into a superheatedvapor. As in FIG. 5, this pump may be optional or require lower pumpingcapacity based on the ability of the collector array to pump fluids viacapillary action.

The expander/generator 608/610 are shown external to the utility unit(unlike in FIG. 5) to illustrate the point that the production of highpressure superheated vapor allows the expander to be directly driven bythe output of the collector array. This cannot be accomplished with theaforementioned low pressure array as a high pressure difference isrequired to extract any useful work from the output superheated vapor.In this regard, a thermal energy conversion system based on highpressure collectors is simpler and less costly to construct andmaintain.

It should be noted that while an expander has been described as a meansfor converting heat into mechanical energy, to be subsequently convertedelectricity, it is not the only option. Other means for the conversionof heat into electricity include but are not limited to, thermoelectricdevices, fuel cell like thermal conversion devices, and thermo electronemission devices. Many versions of these approaches exist and are invarious stages of development by those skilled in the art of suchcomponents and processes. All of these approaches may be incorporatedinto the solar thermal conversion systems described above with varyingconversion efficiencies based on the output temperature of the solararray, the condensing temperature of the environment, and the particularcharacteristics of the thermo-conversion technology.

Referring now to FIG. 7, an integrated application illustrating how theutilities generated by a solar thermal conversion system can beexploited is shown. Symbolic block 700, represents a solar thermallydriven UGU comprising many of the components already described in thisspecification including, a solar collector array 704 (driven by the sun702), thermal storage unit 706, and UGU 710. These combined representthe solar thermal conversion system already described. While theconnecting heat transfer loops are not shown, they are implicit in thisdiagram and thus the aforementioned components are thermally coupled ina manner described earlier so that heat input from the solar flux sourceis converted and output in the form of electricity and cooling resource(via a chilled fluid loop) from UGU 710. One additional component is thehydrocarbon fuel supplemental heat source 708. This component generatesheat by the combustion of a hydrocarbon fuels such as natural gas,biofuels or fuel oil. This heat source provides additional oralternative heat to the solar thermal conversion system should thethermal storage unit 706, prove inadequate and the solar flux source orsolar collector array be compromised due to inclement weather or someother reason. Hydrocarbon fuel supplemental heat source 708, is alsocoupled thermally to the system so that its heat can be supplied in thesame way the heat from the collector array and the storage unit isincorporated.

Symbolic block 712 is a facility which exploits the electricity andcooling utility output by the UGU 710. In this example the facility isin the form of a data center comprising, an array of computational unitsand/or data storage units and associated data communications hardwarerepresented by hardware array 714. Data centers are facilities operatedto handle large data processing tasks driven by the informationtechnology needs of users 718, which include a variety of businesses andcommercial entities ranging from banking to internet hosting and websearching. The primary inputs of data centers are in the form ofelectricity and a cooling resource, the latter being used to dissipatethe tremendous heat which is generated during the course of operatingthe components comprising hardware array 714. Their primary output is inthe form of electronic data exchanged via one or more of several dataexchange means 716, including fiber optic data links, microwave datalinks, and more conventional signal carrying conductive cable arrays,among others. Data centers are historically located near sources ifinexpensive energy (hydroelectric dams for example) and access points tohigh bandwidth communication nodes (fiber optic hubs). In generalproximity to the energy source takes priority as the cost toconstruct-high tension lines capable of transmitting the large amountsof power required are more expensive than installing the fiber opticcables, or other data exchange mechanism, required to transmit largeamounts of data.

Given that the highest levels of solar flux are generally available inremote desert locations, the optimal performance of solar thermalconversion systems is achieved by locating such generation facilitiesfar away from where their power could be utilized. This locationalrequirement increases the cost of such facilities since the constructionand permitting process for the related high tension transmissioncapacity adds cost, complexity, and delays. Locating an integratedfacility, combining the utility generation capacity of block 700 withthe utility consuming and data processing capability of block 712, atthe remote location where the solar flux is high can reduce costs. Theoverall cost reduction comes about due to eliminating the need toestablish high tension transmission capacity, which is very high, at theprice of adding the requisite data exchange means, which is very low.The lower cost of the data exchange means comes about as a result of thelower physical footprint and associated infrastructure require toinstall some combination of fiber optic, microwave, or other means fordata exchange.

Referring now to FIG. 8, a solar thermal system dedicated to producing aheating and/or cooling resource is shown. Solar collector array 802 isilluminated from the sun 800, to produce a high temperature workingfluid vapor stream into vapor conduit 804. Thermal storage unit 806, asdescribed in the earlier Figures, can be used to store excess heat andrelease it as needed. The working fluid vapor passes through utilitygeneration unit (UGU) 808 where, after imparting some portion of itsheat, it is condensed and is pumped by optional fluid pump 810, back tothe solar collector array. UGU 808 is comprised of one of a variety ofthermally driven chiller units which are well understood by thoseskilled in the art of manufacturing such components which are bothcommercially available and under development. Such chiller include burare not limited to absorption chillers, adsorption chillers, and jetvacuum chilling processes. Another approach involves using an expander,of the type described earlier, to mechanically drive a compressor unitas the basis for a conventional vapor compression refrigeration cycle. Asolar thermal conversion system of this sort can benefit from the smallphysical footprint of the planar solar collectors described above,facilitating roof mounted installations and providing high quality heatwithout the need for tracking or concentrating optics.

1. A method for heating a heat transfer fluid, comprising: exposing aheat core to incident radiation to cause heating of said heat core,whereupon the heat core emits infrared radiation; introducing a heattransfer fluid into a wicking layer spaced from the heat core to absorbthe infrared radiation emitted by the heat core, whereupon at least someof the heat transfer fluid is converted into a vapor that enters theheat core; heating the vapor in the heat core; and extracting the heatedvapor to perform work.
 2. The method of claim 1, wherein heating thevapor comprises superheating the vapor.
 3. The method of claim 1,further comprising controlling a rate at which the heat transfer fluidis introduced into the wicking layer to ensure wetness of all portionsof the wicking layer.
 4. A solar collector, comprising: a heat core toconvert incident radiation into heat; a wicking layer spaced from theheat core to absorb infrared radiation emitted by the heat core due tothe conversion of incident radiation into heat; an inlet to introduce aheat transfer fluid into the wicking layer; wherein the absorption ofthe infrared radiation is by the heat transfer fluid in the wickinglayer and causes a portion of the heat transfer fluid to enter into avapor phase thereof which propagates into the heat core where itundergoes heating; and an outlet to transport the heated vapor phase ofthe heat transfer fluid out of the collector.
 5. The solar collector ofclaim 4, wherein heat transfer fluid lost from the wicking layer throughconversion into the vapor phase is replaced through a capillary actionthat pumps more heat transfer fluid into the wicking layer through theinlet.
 6. The solar collector of claim 5, which is tuned in terms ofability of the heat core to convert incident radiation into heat,wicking capacity of the wicking layer, properties of the heat transferfluid, separation distance between the heat core and the wicking layer,and cross-section of the inlet to ensure that all portions of thewicking layer remain wet with heat transfer fluid during operation. 7.The solar collector of claim 4, further comprising a housing for theheat core, and the wicking layer lines an internal surface of thehousing.
 8. The solar collector of claim 7, wherein the housing isplanar.
 9. The solar collector of claim 7, wherein the housing iscylindrical.
 10. The solar collector of claim 7, wherein a portion ofthe housing that is operatively exposed to incident radiation in theform of solar flux is transparent to the incident radiation thereby todefine a window.
 11. The solar collector of claim 10, wherein saidwindow is treated with an anti-reflective material.
 12. The solarcollector of claim 4, wherein the wicking layer comprises a porousmaterial.
 13. The solar collector of claim 12, wherein the porousmaterial comprises film laced with a network of continuousinterconnected passages to create a wicking action through capillaryforces.
 14. The solar collector of claim 4, wherein the wicking layercomprises a surface structured material.
 15. The solar collector ofclaim 14, wherein the surface structured material comprises surfacegrooves to facilitate a capillary pumping action.
 16. The solarcollector of claim 5, wherein the wicking material facing the housing istransparent to visible light and has an index of refraction that ismatched to that of the heat transfer fluid.
 11. The solar collector ofclaim 4, wherein the heat core comprises a thermally conducting metal ora carbon foam matrix.
 18. The solar collector of claim 17, wherein theheat core is treated to make it light absorbing.
 19. The solar collectorof claim 4, wherein the heat core comprises a thermally conductive fillmaterial having interstitial spaces to promote conductive heat transferto the vapor phase of the heat transfer fluid.
 20. The solar collectorof claim 17, wherein the heat core comprises an axial passage extendingthrough the fill material.
 21. The solar collector of claim 18, whereinthe heat core comprises a pair of metal plates each comprisinginterstitial spaces to promote conductive heat transfer to the vaporphase of the heat transfer fluid, the fill material being located withinthe metal plates.
 22. The solar collector of claim 4, wherein the heatcore comprises a non-porous hollow cylinder filled with a porousmaterial having interstitial spaces to promote conductive heat transferto the vapor phase of the heat transfer fluid.
 23. The solar collectorof claim 22, wherein the hollow cylinder is metallic and is able towithstand pressures at least 20 bar.
 24. The solar collector of claim23, wherein the heat core comprises an egress end that is hermeticallysealed with the outlet.
 25. The solar collector of claim 23, wherein theheat core comprises an ingress end through which the vapor phase of theheat transfer fluid enters the heat core, said ingress end being pluggedby a capillary pump.
 26. The solar collector of claim 25, wherein thecapillary pump comprises a porous material designed to perform a pumpingaction on the heat transfer fluid due to variations in pore size. 27.The solar collector of claim 24, wherein the porous material comprisesat least two layers in contact with each other, each layer having poresof a different size.
 28. An energy system, comprising: an array of solarcollectors; a first heat transfer loop coupled to the array to provide arecirculation path for heated heat transfer fluid from and to the array;and a second heat transfer loop comprising at least one heat exchangerto extract heat from the heated heat transfer fluid in the first heattransfer loop to perform work; wherein at least one solar collector,comprises: a heat core to convert incident radiation into heat; awicking layer spaced from the heat core to absorb infrared radiationemitted by the heat core due to the conversion of incident radiationinto heat; an inlet to introduce a heat transfer fluid ‘into the wickinglayer; wherein the absorption of the infrared radiation is by the heattransfer fluid in the wicking layer, and causes a portion of the heattransfer fluid to enter into a vapor phase thereof which propagates intothe heat core where it undergoes heating; and an outlet to transport theheated vapor phase of the heat transfer fluid out of the collector. 29.The energy system of claim 28, wherein the first heat transfer loopcomprises an energy accumulation device to store heat from the heatedheat transfer fluid in the first heat transfer loop.
 30. The energysystem of claim 28, wherein the energy accumulator selectively adds heatto the heated heat transfer fluid in the first heat transfer loop. 31.An energy system, comprising: an array of solar collectors; a heattransfer loop coupled to the array to provide a recirculation path forheated heat transfer fluid from and to the array; and at least one heatexchanger positioned within the heat transfer loop to extract heat fromthe heated heat transfer fluid; wherein at least one solar collector insaid array comprises: a heat core to convert incident radiation intoheat; a wicking layer spaced from the heat core to absorb infraredradiation emitted by the heat core due to the conversion of incidentradiation into heat; an inlet to introduce a heat transfer fluid intothe wicking layer; wherein the absorption of the infrared radiation isby the heat transfer fluid in the wicking layer, and causes a portion ofthe heat transfer fluid to enter into a vapor phase thereof whichpropagates into the heat core where it undergoes heating; and an outletto transport the heated vapor phase of the working fluid out of thecollector.
 32. The energy system of claim 31, wherein the heat transferloop comprises an energy accumulation device to store heat from theheated working fluid in the first heat transfer loop.
 33. The energysystem of claim 31, wherein the energy accumulator selectively adds heatto the heated working fluid in the heat transfer loop.